This invention relates generally to apparatus for separating gas mixtures by pressure swing adsorption and relates more particularly to the arrangement of valves and other working components within such an apparatus.
The type of pressure swing adsorption apparatus with which this invention is concerned includes a pair of adsorbers each having a fixed bed of adsorbent material and an inlet and an outlet accommodating a flow of gas therethrough. The adsorbent material of each adsorber is adapted to fractionate at least one constituent from a gaseous mixture when the gaseous mixture is sequentially directed into the inlet of one adsorber so that the one adsorber performs adsorption while the other adsorber is simultaneously purged of adsorbed constituent with product gas withdrawn from the one adsorber and then the gaseous mixture is directed from the feed stream into the inlet of the other adsorber so that the other adsorber performs adsorption while the one adsorber is simultaneously purged of adsorbed constituent with product gas withdrawn from the outlet of the other adsorber. One such pressure swing adsorption apparatus is utilized for separating nitrogen from air delivered from an air source and for providing a product stream of relatively high purity oxygen.
For purposes of directing the flow of the gaseous mixture or product gas between the adsorbers in a desired manner, the adsorption apparatus commonly includes feed valving means, a purge loop and equalization valving means. The feed valving means is operatively connected between the inlets of the adsorbers and the feed stream for directing gaseous mixture from the feed stream into the inlet of one and the other adsorber in an alternating fashion so that only one adsorber at a time performs adsorption and produces product gas. The purge loop is connected between the outlets of the adsorbers for permitting product gas exiting the outlet of the adsorber performing adsorption to enter the outlet of the other adsorber for purging the other adsorber of adsorbed constituent and so that while one adsorber performs adsorption, the other adsorber undergoes desorption or regeneration. The equalization valving means is connected between the outlets of the adsorbers for equalizing the internal pressures of the adsorbers between preselected stages of apparatus operation.
Furthermore, waste valving means are associated with the inlets of the adsorbers through which product-depleted waste gas is discharged from the adsorber undergoing regeneration. For controlling the sequencing of the apparatus valving means, timing devices are commonly and operatively connected to the valving means for controlling the time periods during which the valving means are actuated and deactuated. Hence, the timing devices provide means by which the operation and various stages of the apparatus are automatically controlled.
It is an object of the present invention to provide a new and improved pressure swing adsorption apparatus wherein working components, such as the aforedescribed valving means of the apparatus are arranged in a manner facilitating service and maintenance of the apparatus.
Another object of the present invention is to provide such an apparatus which is uncomplicated in structure yet effective in operation.